Roasting-quenching pretreatment in the calcination process to improve the purity of rice husk bio-silica

Calcination is a simple method for producing silica from rice husk (RH), where the effectiveness of removing impurities (especially potassium) before the calcination process is one of the keys in obtaining high purity silica levels. This study examined the effect of the roasting-quenching process on the purity level of silica obtained through the calcination method. Based on trace metal measurements with inductively coupled plasma mass spectrometry, high purity silica has been obtained, to be 99.93%, from the sample with a processing route: Roasting-quenching at 400°C, 1M HCl leaching, and continued with the calcination process at 650°C. However, since energy saving is a policy that must be prioritized, then the best route is roastingquenching at 300°C, 1M HCl, leaching, and calcining at 600°C. has been obtained, to be 99.93%, from the sample with a processing route: Roasting-quenching at 400°C, 1M HCl leaching, and continued with the calcination process at 650°C. However, since energy saving is a policy that must be prioritized, then the best route is roastingquenching at 300°C, 1M HCl, leaching, and calcining at 600°C.